| Version 5 (modified by mitty, 13 years ago) (diff) |
|---|
10/05
trace getpid() syscall with GDB
- windell57:x86_64 s0711489$ gdb
(gdb) set logging file gdb.getpid.log (gdb) set logging on Copying output to gdb.getpid.log. (gdb) file vmlinux Reading symbols from /home/ugrad/07/s0711489/coursework/KernelHack/linux-2.6.35.14/x86_64/vmlinux...(no debugging symbols found)...done. (gdb) b sys_getpid Breakpoint 1 at 0xffffffff81048ce4: file kernel/timer.c, line 1344. (gdb) target remote localhost:8864 Remote debugging using localhost:8864 0xffffffff810097a9 in native_safe_halt () at /home/ugrad/07/s0711489/coursework/KernelHack/linux-2.6.35.14/x86_64/arch/x86/include/asm/irqflags.h:49 49 asm volatile("sti; hlt": : :"memory"); (gdb) c Continuing. Breakpoint 1, sys_getpid () at kernel/timer.c:1344 - => attachment:gdb.getpid.log
- on VM guest
- s0711489@ubuntu-lucid64:~/coursework/KernelHack/02$ ./getpid
getpid() -> 2143
- s0711489@ubuntu-lucid64:~/coursework/KernelHack/02$ ./getpid
trace log with source list and print data
- windell57:x86_64 s0711489$ gdb
(gdb) file vmlinux Reading symbols from /home/ugrad/07/s0711489/coursework/KernelHack/linux-2.6.35.14/x86_64/vmlinux...(no debugging symbols found)...done. (gdb) b sys_getpid Breakpoint 1 at 0xffffffff81048ce4: file kernel/timer.c, line 1344. (gdb) target remote localhost:8864 Remote debugging using localhost:8864 0xffffffff810097a9 in native_safe_halt () at /home/ugrad/07/s0711489/coursework/KernelHack/linux-2.6.35.14/x86_64/arch/x86/include/asm/irqflags.h:49 49 asm volatile("sti; hlt": : :"memory"); (gdb) c Continuing. Breakpoint 1, sys_getpid () at kernel/timer.c:1344 1344 { (gdb) bt #0 sys_getpid () at kernel/timer.c:1344 #1 0xffffffff810029eb in ?? () #2 0x0000000000000246 in ?? () #3 0x00007fff70d418e0 in ?? () #4 0x00007f6c11b19210 in ?? () #5 0x00007f6c11b05300 in ?? () #6 0x0000000000000027 in ?? () #7 0x0000000000000000 in ?? () (gdb) l 1339 * which case the tgid is the same in all threads of the same group. 1340 * 1341 * This is SMP safe as current->tgid does not change. 1342 */ 1343 SYSCALL_DEFINE0(getpid) 1344 { 1345 return task_tgid_vnr(current); 1346 } 1347 1348 /* (gdb) s 1345 return task_tgid_vnr(current); (gdb) get_current () at /home/ugrad/07/s0711489/coursework/KernelHack/linux-2.6.35.14/x86_64/arch/x86/include/asm/current.h:14 14 return percpu_read_stable(current_task); (gdb) l 9 10 DECLARE_PER_CPU(struct task_struct *, current_task); 11 12 static __always_inline struct task_struct *get_current(void) 13 { 14 return percpu_read_stable(current_task); 15 } 16 17 #define current get_current() 18 (gdb) bt #0 get_current () at /home/ugrad/07/s0711489/coursework/KernelHack/linux-2.6.35.14/x86_64/arch/x86/include/asm/current.h:14 #1 sys_getpid () at kernel/timer.c:1345 #2 0xffffffff810029eb in ?? () #3 0x0000000000000246 in ?? () #4 0x00007fff63204890 in ?? () #5 0x00007fc615a98210 in ?? () #6 0x00007fc615a84300 in ?? () #7 0x0000000000000027 in ?? () #8 0x0000000000000000 in ?? () (gdb) p current_task Cannot access memory at address 0xb540 (gdb) ptype current_task type = struct task_struct { (snip) (gdb) s sys_getpid () at kernel/timer.c:1344 1344 { (gdb) l 1339 * which case the tgid is the same in all threads of the same group. 1340 * 1341 * This is SMP safe as current->tgid does not change. 1342 */ 1343 SYSCALL_DEFINE0(getpid) 1344 { 1345 return task_tgid_vnr(current); 1346 } 1347 1348 /* (gdb) bt #0 sys_getpid () at kernel/timer.c:1344 #1 0xffffffff810029eb in ?? () #2 0x0000000000000246 in ?? () #3 0x00007fff63204890 in ?? () #4 0x00007fc615a98210 in ?? () #5 0x00007fc615a84300 in ?? () #6 0x0000000000000027 in ?? () #7 0x0000000000000000 in ?? () (gdb) s 1345 return task_tgid_vnr(current); (gdb) s task_tgid_vnr (tsk=0xffff88001bbe5880) at include/linux/sched.h:1606 1606 { (gdb) l 1601 } 1602 1603 pid_t task_tgid_nr_ns(struct task_struct *tsk, struct pid_namespace *ns); 1604 1605 static inline pid_t task_tgid_vnr(struct task_struct *tsk) 1606 { 1607 return pid_vnr(task_tgid(tsk)); 1608 } 1609 1610 (gdb) bt #0 task_tgid_vnr (tsk=0xffff88001bbe5880) at include/linux/sched.h:1606 #1 0xffffffff81048cf6 in sys_getpid () at kernel/timer.c:1345 #2 0xffffffff810029eb in ?? () #3 0x0000000000000246 in ?? () #4 0x00007fff63204890 in ?? () #5 0x00007fc615a98210 in ?? () #6 0x00007fc615a84300 in ?? () #7 0x0000000000000027 in ?? () #8 0x0000000000000000 in ?? () (gdb) p tsk $2 = (struct task_struct *) 0xffff88001bbe5880 (gdb) ptype tsk type = struct task_struct { (snip) pid_t pid; pid_t tgid; (snip) struct task_struct *group_leader; struct list_head ptraced; struct list_head ptrace_entry; struct pid_link pids[3]; (snip) (gdb) ptype tsk->group_leader->pids type = struct pid_link { struct hlist_node node; struct pid *pid; } [3] (snip) (gdb) s 1607 return pid_vnr(task_tgid(tsk)); (gdb) 1606 { (gdb) 1607 return pid_vnr(task_tgid(tsk)); (gdb) pid_vnr (pid=0xffff88001fb55400) at kernel/pid.c:444 444 { (gdb) bt #0 pid_vnr (pid=0xffff88001fb55400) at kernel/pid.c:444 #1 0xffffffff81048783 in task_tgid_vnr (tsk=<value optimized out>) at include/linux/sched.h:1607 #2 0xffffffff81048cf6 in sys_getpid () at kernel/timer.c:1345 #3 0xffffffff810029eb in ?? () #4 0x0000000000000246 in ?? () #5 0x00007fff63204890 in ?? () #6 0x00007fc615a98210 in ?? () #7 0x00007fc615a84300 in ?? () #8 0x0000000000000027 in ?? () #9 0x0000000000000000 in ?? () (gdb) l 439 } 440 return nr; 441 } 442 443 pid_t pid_vnr(struct pid *pid) 444 { 445 return pid_nr_ns(pid, current->nsproxy->pid_ns); 446 } 447 EXPORT_SYMBOL_GPL(pid_vnr); 448 (gdb) ptype pid type = struct pid { atomic_t count; unsigned int level; struct hlist_head tasks[3]; struct rcu_head rcu; struct upid numbers[1]; } * (gdb) up #1 0xffffffff81048783 in task_tgid_vnr (tsk=<value optimized out>) at include/linux/sched.h:1607 1607 return pid_vnr(task_tgid(tsk)); (gdb) ptype tsk->nsproxy->pid_ns type = struct pid_namespace { struct kref kref; struct pidmap pidmap[128]; int last_pid; struct task_struct *child_reaper; struct kmem_cache *pid_cachep; unsigned int level; struct pid_namespace *parent; struct vfsmount *proc_mnt; struct bsd_acct_struct *bacct; } * (gdb) down #0 pid_vnr (pid=0xffff88001fb55400) at kernel/pid.c:444 444 { (gdb) s 445 return pid_nr_ns(pid, current->nsproxy->pid_ns); (gdb) get_current (pid=0xffff88001fb55400) at /home/ugrad/07/s0711489/coursework/KernelHack/linux-2.6.35.14/x86_64/arch/x86/include/asm/current.h:14 14 return percpu_read_stable(current_task); (gdb) p current_task Cannot access memory at address 0xb540 (gdb) s pid_vnr (pid=0xffff88001fb55400) at kernel/pid.c:445 445 return pid_nr_ns(pid, current->nsproxy->pid_ns); (gdb) s 444 { (gdb) 445 return pid_nr_ns(pid, current->nsproxy->pid_ns); (gdb) pid_nr_ns (pid=0xffff88001fb55400, ns=0xffffffff8181bfe0) at kernel/pid.c:431 431 { (gdb) bt #0 pid_nr_ns (pid=0xffff88001fb55400, ns=0xffffffff8181bfe0) at kernel/pid.c:431 #1 0xffffffff81052db6 in pid_vnr (pid=0xffff88001fb55400) at kernel/pid.c:445 #2 0xffffffff81048783 in task_tgid_vnr (tsk=<value optimized out>) at include/linux/sched.h:1607 #3 0xffffffff81048cf6 in sys_getpid () at kernel/timer.c:1345 #4 0xffffffff810029eb in ?? () #5 0x0000000000000246 in ?? () #6 0x00007fff63204890 in ?? () #7 0x00007fc615a98210 in ?? () #8 0x00007fc615a84300 in ?? () #9 0x0000000000000027 in ?? () #10 0x0000000000000000 in ?? () (gdb) l 426 return pid; 427 } 428 EXPORT_SYMBOL_GPL(find_get_pid); 429 430 pid_t pid_nr_ns(struct pid *pid, struct pid_namespace *ns) 431 { 432 struct upid *upid; 433 pid_t nr = 0; 434 435 if (pid && ns->level <= pid->level) { (gdb) l 436 upid = &pid->numbers[ns->level]; 437 if (upid->ns == ns) 438 nr = upid->nr; 439 } 440 return nr; 441 } 442 443 pid_t pid_vnr(struct pid *pid) 444 { 445 return pid_nr_ns(pid, current->nsproxy->pid_ns); (gdb) ptype pid type = struct pid { atomic_t count; unsigned int level; struct hlist_head tasks[3]; struct rcu_head rcu; struct upid numbers[1]; } * (gdb) ptype ns type = struct pid_namespace { struct kref kref; struct pidmap pidmap[128]; int last_pid; struct task_struct *child_reaper; struct kmem_cache *pid_cachep; unsigned int level; struct pid_namespace *parent; struct vfsmount *proc_mnt; struct bsd_acct_struct *bacct; } * type = struct upid { int nr; struct pid_namespace *ns; struct hlist_node pid_chain; } * (gdb) ptype pid_t type = int (gdb) p ns->level $5 = 0 (gdb) p pid->level $6 = 0 (gdb) p ns->level <= pid->level $7 = 1 (gdb) p ns $8 = (struct pid_namespace *) 0xffffffff8181bfe0 (gdb) p &pid->numbers[ns->level] $9 = (struct upid *) 0xffff88001fb55430 (gdb) p (&pid->numbers[ns->level])->ns $10 = (struct pid_namespace *) 0xffffffff8181bfe0 (gdb) info locals upid = <value optimized out> nr = <value optimized out> (gdb) p nr $11 = <value optimized out> (gdb) p (&pid->numbers[ns->level])->nr $12 = 2225 (gdb) s 435 if (pid && ns->level <= pid->level) { (gdb) 431 { (gdb) 435 if (pid && ns->level <= pid->level) { (gdb) 436 upid = &pid->numbers[ns->level]; (gdb) 437 if (upid->ns == ns) (gdb) p upid $13 = (struct upid *) 0xffff88001fb55430 (gdb) s 438 nr = upid->nr; (gdb) p upid->ns == ns $14 = 1 (gdb) p nr $15 = <value optimized out> (gdb) p upid->nr $16 = 2225 (gdb) s 441 } (gdb) pid_vnr (pid=<value optimized out>) at kernel/pid.c:446 446 } (gdb) s task_tgid_vnr (tsk=<value optimized out>) at include/linux/sched.h:1608 1608 } (gdb) sys_getpid () at kernel/timer.c:1346 1346 } (gdb) sys_getpid () at kernel/timer.c:1345 1345 return task_tgid_vnr(current); (gdb) sys_getpid () at kernel/timer.c:1346 1346 } (gdb)
- on VM guest
- s0711489@ubuntu-lucid64:~/coursework/KernelHack/02$ ./getpid
getpid() -> 2225
- s0711489@ubuntu-lucid64:~/coursework/KernelHack/02$ ./getpid
location of functions on source file
- windell57:x86_64 s0711489$ grep percpu_read_stable -r .
(snip) ./arch/x86/include/asm/percpu.h:#define percpu_read_stable(var) percpu_from_op("mov", var, "p" (&(var))) (snip)
- windell57:x86_64 s0711489$ grep task_tgid -r .
(snip) ./include/linux/sched.h:static inline struct pid *task_tgid(struct task_struct *task) (snip)
- include/linux/sched.h
static inline struct pid *task_tgid(struct task_struct *task) { return task->group_leader->pids[PIDTYPE_PID].pid; }
get_current function
- windell57:02 s0711489$ gcc -E ../linux-2.6.35.14/x86_64/arch/x86/include/asm/current.h -I ~/coursework/KernelHack/linux-2.6.35.14/x86_64/include -I ~/coursework/KernelHack/linux-2.6.35.14/x86_64/arch/x86/include/ > current.h
In file included from /home/ugrad/07/s0711489/coursework/KernelHack/linux-2.6.35.14/x86_64/arch/x86/include/asm/percpu.h:44, from ../linux-2.6.35.14/x86_64/arch/x86/include/asm/current.h:5: /home/ugrad/07/s0711489/coursework/KernelHack/linux-2.6.35.14/x86_64/include/linux/kernel.h:733:2: warning: #warning Attempt to use kernel headers from user space, see http: - pre-processed arch/x86/include/asm/current.h
static __always_inline struct task_struct *get_current(void) { return ({ typeof(current_task) pfo_ret__; switch (sizeof(current_task)) { case 1: asm("mov" "b ""%P" "1"",%0" : "=q" (pfo_ret__) : "p" (&(current_task))); break; case 2: asm("mov" "w ""%P" "1"",%0" : "=r" (pfo_ret__) : "p" (&(current_task))); break; case 4: asm("mov" "l ""%P" "1"",%0" : "=r" (pfo_ret__) : "p" (&(current_task))); break; case 8: asm("mov" "q ""%P" "1"",%0" : "=r" (pfo_ret__) : "p" (&(current_task))); break; default: __bad_percpu_size(); } pfo_ret__; }); }
10/12
tee system call
- http://linuxjm.sourceforge.jp/html/LDP_man-pages/man2/tee.2.html
#define _GNU_SOURCE #include <fcntl.h> #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <errno.h> #include <limits.h> int main(int argc, char *argv[]) { int fd; int len, slen; if (argc != 2) { fprintf(stderr, "Usage: %s <file>\n", argv[0]); exit(EXIT_FAILURE); } fd = open(argv[1], O_WRONLY | O_CREAT | O_TRUNC, 0644); if (fd == -1) { perror("open"); exit(EXIT_FAILURE); } do { /* * tee stdin to stdout. */ len = tee(STDIN_FILENO, STDOUT_FILENO, INT_MAX, SPLICE_F_NONBLOCK); if (len < 0) { if (errno == EAGAIN) continue; perror("tee"); exit(EXIT_FAILURE); } else if (len == 0) break; /* * Consume stdin by splicing it to a file. */ while (len > 0) { slen = splice(STDIN_FILENO, NULL, fd, NULL, len, SPLICE_F_MOVE); if (slen < 0) { perror("splice"); break; } len -= slen; } } while (1); close(fd); exit(EXIT_SUCCESS); }
- Ubuntu lucid(2.6.32-33-generic)やvanilla 2.6.35.14ではサンプルコードのまま正常に使える
- mitty@ubuntu64:~/coursework/KernelHack/02$ cat tee.c | ./tee hoge | wc
58 130 1217
- mitty@ubuntu64:~/coursework/KernelHack/02$ cat tee.c | ./tee hoge | wc
- CentOS 5.7(2.6.18-238.19.1.el5.centos.plusPAE or 2.6.18-274.3.1.el5)ではspliceがエラーになる
- viola01:02 s0711489$ cat tee.c | ./tee hoge | wc
viola01:02 s0711489$ cat tee.c | ./tee hoge | wc splice: Invalid argument splice: Invalid argument splice: Invalid argument splice: Invalid argument splice: Invalid argument splice: Invalid argument splice: Invalid argument splice: Invalid argument splice: Invalid argument ....
- viola01:02 s0711489$ cat tee.c | ./tee hoge | wc
- Ubuntu上でも、strace出来ない
- mitty@ubuntu64:~/coursework/KernelHack/02$ strace -f -o sh.log sh -c 'cat tee.c | ./tee hoge | wc'
- mitty@ubuntu64:~/coursework/KernelHack/02$ less sh.log
(snip) 1611 <... tee resumed> ) = -1 EAGAIN (Resource temporarily unavailable) 1611 tee(0, 0x1, 0x7fffffff, 0x2) = -1 EAGAIN (Resource temporarily unavailable) 1611 tee(0, 0x1, 0x7fffffff, 0x2) = -1 EAGAIN (Resource temporarily unavailable) 1611 tee(0, 0x1, 0x7fffffff, 0x2) = -1 EAGAIN (Resource temporarily unavailable) 1611 tee(0, 0x1, 0x7fffffff, 0x2) = -1 EAGAIN (Resource temporarily unavailable) 1611 tee(0, 0x1, 0x7fffffff, 0x2) = -1 EAGAIN (Resource temporarily unavailable) 1611 tee(0, 0x1, 0x7fffffff, 0x2) = -1 EAGAIN (Resource temporarily unavailable) (snip)
- GDBによるステップ実行は、3000行ほど実行してみたがguest側で結果が出力されないので、断念
10/14
getcpu system call
- http://www.kernel.org/doc/man-pages/online/pages/man2/getcpu.2.html
- http://www.linuxquestions.org/questions/programming-9/determine-what-cpu-my-thread-is-on-817697/
- getcpu system callはには存在しない
- arch/x86/include/asm/unistd_64.h
#define __IGNORE_getcpu /* implemented as a vsyscall */
- arch/x86/include/asm/unistd_64.h
- s0711489@ubuntu-lucid64:~/coursework/KernelHack/02$ cat > getcpu.c
#define _GNU_SOURCE /* See feature_test_macros(7) */ #include <linux/getcpu.h> #include <stdio.h> int main (void) { int c, s; s = getcpu(&c, NULL, NULL); printf ("getcpu() -> %d\n", (s == -1) ? s : c); }
- s0711489@ubuntu-lucid64:~/coursework/KernelHack/02$ gcc getcpu.c -o getcpu
getcpu.c:1:26: error: linux/getcpu.h: No such file or directory
i386
- s0711489@ubuntu-lucid:~$ sudo /mnt/hgfs/tools/install.sh
+ cat /mnt/hgfs/linux-2.6.35.14/include/config/kernel.release + VERSION=2.6.35.14 + echo Install Linux Kernel version 2.6.35.14 Install Linux Kernel version 2.6.35.14 + cd /mnt/hgfs/linux-2.6.35.14/ + make install sh /mnt/hgfs/linux-2.6.35.14/arch/x86/boot/install.sh 2.6.35.14 arch/x86/boot/bzImage \ System.map "/boot" + make modules_install INSTALL arch/x86/kernel/test_nx.ko INSTALL drivers/scsi/scsi_wait_scan.ko INSTALL net/netfilter/xt_mark.ko DEPMOD 2.6.35.14 + mkinitramfs -o /boot/initrd.img-2.6.35.14 2.6.35.14 + update-grub Generating grub.cfg ... Found linux image: /boot/vmlinuz-2.6.35.14 Found initrd image: /boot/initrd.img-2.6.35.14 Found linux image: /boot/vmlinuz-2.6.32-33-generic Found initrd image: /boot/initrd.img-2.6.32-33-generic Found memtest86+ image: /boot/memtest86+.bin done + echo Install Kernel Headers to /lib/modules/2.6.35.14/build Install Kernel Headers to /lib/modules/2.6.35.14/build + date +%Y%m%d + mv /lib/modules/2.6.35.14/build /lib/modules/2.6.35.14/build-20111014 + cd /mnt/hgfs/ + tar c --files-from - + tar x -C /lib/modules/2.6.35.14/ + egrep -v vmlinu + egrep -v .o$ + find linux-2.6.35.14 -type f + mv /lib/modules/2.6.35.14/linux-2.6.35.14 /lib/modules/2.6.35.14/build + uname -a Linux ubuntu-lucid 2.6.32-33-generic #72-Ubuntu SMP Fri Jul 29 21:08:37 UTC 2011 i686 GNU/Linux - s0711489@ubuntu-lucid:~$ sudo vmware-config-tools.pl --default
- s0711489@ubuntu-lucid:~$ cat > getcpu.c
#define _GNU_SOURCE #include <stdio.h> #include <sys/syscall.h> #include <unistd.h> #include <errno.h> #include <string.h> int main( void ) { int cpu = syscall(SYS_getcpu); if (cpu < 0) { printf( "Error: errno = %d\n", errno ); fflush(stdout); printf( "Error: errno: %s\n", strerror(errno) ); fflush(stdout); return -1; } printf( "cpu = %d\n", cpu ); return 0; }
- s0711489@ubuntu-lucid:~$ gcc getcpu.c -o getcpu
- s0711489@ubuntu-lucid:~$ ./getcpu
Error: errno = 14 Error: errno: Bad address
- うまく動かない
getuid system call
- windell57:x86_64 s0711489$ gdb
(gdb) set logging file gdb.getuid.log (gdb) set logging on Copying output to gdb.getuid.log. (gdb) file vmlinux Reading symbols from /home/ugrad/07/s0711489/coursework/KernelHack/linux-2.6.35.14/x86_64/vmlinux...(no debugging symbols found)...done. (gdb) b sys_getuid Breakpoint 1 at 0xffffffff81048d17: file kernel/timer.c, line 1366. (gdb) target remote localhost:8864 Remote debugging using localhost:8864 0xffffffff810097a9 in native_safe_halt () at /home/ugrad/07/s0711489/coursework/KernelHack/linux-2.6.35.14/x86_64/arch/x86/include/asm/irqflags.h:49 49 asm volatile("sti; hlt": : :"memory"); (gdb) c Continuing. Breakpoint 1, sys_getuid () at kernel/timer.c:1366 1366 { (gdb) s 1368 return current_uid(); (gdb) get_current () at /home/ugrad/07/s0711489/coursework/KernelHack/linux-2.6.35.14/x86_64/arch/x86/include/asm/current.h:14 14 return percpu_read_stable(current_task); (gdb) 1368 return current_uid(); (gdb) sys_getuid () at kernel/timer.c:1366 1366 { (gdb) 1368 return current_uid(); (gdb) get_current () at kernel/timer.c:1368 1368 return current_uid(); (gdb) sys_getuid () at kernel/timer.c:1369 1369 } (gdb) Program received signal SIGINT, Interrupt. 0xffffffff810097a9 in native_safe_halt () at /home/ugrad/07/s0711489/coursework/KernelHack/linux-2.6.35.14/x86_64/arch/x86/include/asm/irqflags.h:49 49 asm volatile("sti; hlt": : :"memory"); (gdb) detach Ending remote debugging. (gdb) quit
- s0711489@ubuntu-lucid64:~/coursework/KernelHack/02$ ./getuid
getuid() -> 1000
trace log with source list and print data
- windell57:x86_64 s0711489$ gdb
(gdb) file vmlinux Reading symbols from /home/ugrad/07/s0711489/coursework/KernelHack/linux-2.6.35.14/x86_64/vmlinux...(no debugging symbols found)...done. (gdb) b sys_getuid Breakpoint 1 at 0xffffffff81048d17: file kernel/timer.c, line 1366. (gdb) target remote localhost:8864 Remote debugging using localhost:8864 0xffffffff810097a9 in native_safe_halt () at /home/ugrad/07/s0711489/coursework/KernelHack/linux-2.6.35.14/x86_64/arch/x86/include/asm/irqflags.h:49 49 asm volatile("sti; hlt": : :"memory"); (gdb) c Continuing. Breakpoint 1, sys_getuid () at kernel/timer.c:1366 1366 { (gdb) bt #0 sys_getuid () at kernel/timer.c:1366 #1 0xffffffff810029eb in ?? () #2 0x0000000000000206 in ?? () #3 0x00007ffff56d6ad0 in ?? () #4 0x00007f8671347210 in ?? () #5 0x00007f8671333300 in ?? () #6 0x0000000000000066 in ?? () #7 0x0000000000000000 in ?? () (gdb) l 1361 1362 return pid; 1363 } 1364 1365 SYSCALL_DEFINE0(getuid) 1366 { 1367 /* Only we change this so SMP safe */ 1368 return current_uid(); 1369 } 1370 (gdb) s 1368 return current_uid(); (gdb) get_current () at /home/ugrad/07/s0711489/coursework/KernelHack/linux-2.6.35.14/x86_64/arch/x86/include/asm/current.h:14 14 return percpu_read_stable(current_task); (gdb) bt #0 get_current () at /home/ugrad/07/s0711489/coursework/KernelHack/linux-2.6.35.14/x86_64/arch/x86/include/asm/current.h:14 #1 sys_getuid () at kernel/timer.c:1368 #2 0xffffffff810029eb in ?? () #3 0x0000000000000206 in ?? () #4 0x00007ffff56d6ad0 in ?? () #5 0x00007f8671347210 in ?? () #6 0x00007f8671333300 in ?? () #7 0x0000000000000066 in ?? () #8 0x0000000000000000 in ?? () (gdb) l 9 10 DECLARE_PER_CPU(struct task_struct *, current_task); 11 12 static __always_inline struct task_struct *get_current(void) 13 { 14 return percpu_read_stable(current_task); 15 } 16 17 #define current get_current() 18 (gdb) p current_task Cannot access memory at address 0xb540 (gdb) ptype current_task type = struct task_struct { (snip ---Type <return> to continue, or q <return> to quit---q Quit (gdb) s 1368 return current_uid(); (gdb) sys_getuid () at kernel/timer.c:1366 1366 { (gdb) bt #0 sys_getuid () at kernel/timer.c:1366 #1 0xffffffff810029eb in ?? () #2 0x0000000000000206 in ?? () #3 0x00007ffff56d6ad0 in ?? () #4 0x00007f8671347210 in ?? () #5 0x00007f8671333300 in ?? () #6 0x0000000000000066 in ?? () #7 0x0000000000000000 in ?? () (gdb) s 1368 return current_uid(); (gdb) get_current () at kernel/timer.c:1368 1368 return current_uid(); (gdb) bt #0 get_current () at kernel/timer.c:1368 #1 sys_getuid () at kernel/timer.c:1368 #2 0xffffffff810029eb in ?? () #3 0x0000000000000206 in ?? () #4 0x00007ffff56d6ad0 in ?? () #5 0x00007f8671347210 in ?? () #6 0x00007f8671333300 in ?? () #7 0x0000000000000066 in ?? () #8 0x0000000000000000 in ?? () (gdb) l 1363 } 1364 1365 SYSCALL_DEFINE0(getuid) 1366 { 1367 /* Only we change this so SMP safe */ 1368 return current_uid(); 1369 } 1370 1371 SYSCALL_DEFINE0(geteuid) 1372 { (gdb) s sys_getuid () at kernel/timer.c:1369 1369 } (gdb) bt #0 sys_getuid () at kernel/timer.c:1369 #1 0xffffffff810029eb in ?? () #2 0x0000000000000206 in ?? () #3 0x00007ffff56d6ad0 in ?? () #4 0x00007f8671347210 in ?? () #5 0x00007f8671333300 in ?? () #6 0x0000000000000066 in ?? () #7 0x0000000000000000 in ?? () (gdb) l 1364 1365 SYSCALL_DEFINE0(getuid) 1366 { 1367 /* Only we change this so SMP safe */ 1368 return current_uid(); 1369 } 1370 1371 SYSCALL_DEFINE0(geteuid) 1372 { 1373 /* Only we change this so SMP safe */ (gdb) p current_uid No symbol "current_uid" in current context. (gdb) ptype current_uid No symbol "current_uid" in current context. (gdb) s Breakpoint 1, sys_getuid () at kernel/timer.c:1366 1366 { (gdb) detach Ending remote debugging.
- include/linux/cred.h
#define current_cred_xxx(xxx) \ ({ \ current->cred->xxx; \ }) #define current_uid() (current_cred_xxx(uid)) #define current_gid() (current_cred_xxx(gid)) (snip)
- ptype of current_task->cred
(gdb) ptype current_task->cred type = const struct cred { atomic_t usage; uid_t uid; gid_t gid; uid_t suid; gid_t sgid; uid_t euid; gid_t egid; uid_t fsuid; gid_t fsgid; unsigned int securebits; kernel_cap_t cap_inheritable; kernel_cap_t cap_permitted; kernel_cap_t cap_effective; kernel_cap_t cap_bset; unsigned char jit_keyring; struct key *thread_keyring; struct key *request_key_auth; struct thread_group_cred *tgcred; void *security; struct user_struct *user; struct group_info *group_info; struct rcu_head rcu; } * (gdb) ptype current_task->cred->uid type = unsigned int
10/19
add new system call (i386)
- windell57:i386 s0711489$ vim arch/x86/include/asm/unistd_32.h
- windell57:i386 s0711489$ vim arch/x86/kernel/syscall_table_32.S
- windell57:i386 s0711489$ vim arch/x86/include/asm/new_hello.h
- windell57:i386 s0711489$ vim arch/x86/kernel/new_hello.c
10/21
add new system call (i386) (cont)
- windell57:i386 s0711489$ vim arch/x86/kernel/new_hello.c
- windell57:i386 s0711489$ vim arch/x86/kernel/Makefile
-
arch/x86/kernel/syscall_table_32.S
337 337 .long sys_rt_tgsigqueueinfo /* 335 */ 338 338 .long sys_perf_event_open 339 339 .long sys_recvmmsg 340 .long sys_new_hello -
arch/x86/kernel/Makefile
131 131 obj-$(CONFIG_PCI_MMCONFIG) += mmconf-fam10h_64.o 132 132 obj-y += vsmp_64.o 133 133 endif 134 135 obj-y += new_hello.o -
arch/x86/kernel/new_hello.c
1 #include <linux/kernel.h> 2 #include <linux/syscalls.h> 3 4 SYSCALL_DEFINE1(new_hello, int, i) { 5 printk(KERN_DEBUG "new_hello() syscall with %d", i); 6 return i; 7 } -
arch/x86/include/asm/unistd_32.h
343 343 #define __NR_rt_tgsigqueueinfo 335 344 344 #define __NR_perf_event_open 336 345 345 #define __NR_recvmmsg 337 346 #define __NR_new_hello 338 346 347 347 348 #ifdef __KERNEL__ 348 349 349 #define NR_syscalls 33 8350 #define NR_syscalls 339 350 351 351 352 #define __ARCH_WANT_IPC_PARSE_VERSION 352 353 #define __ARCH_WANT_OLD_READDIR -
arch/x86/include/asm/new_hello.h
1 #ifndef _ASM_X86_NEW_HELLO_H 2 #define _ASM_X86_NEW_HELLO_H 3 4 #include <asm/unistd.h> 5 #define new_hello(x) syscall(__NR_new_hello, x) 6 7 #endif /* _ASM_X86_NEW_HELLO_H */
-
- windell57:i386 s0711489$ make
Kernel: arch/x86/boot/bzImage is ready (#2)
- windell57:i386 s0711489$ make modules
- s0711489@ubuntu-lucid:~$ sudo /mnt/hgfs/tools/install.sh
- s0711489@ubuntu-lucid:~$ sudo reboot
Linux ubuntu-lucid 2.6.35.14 #2 SMP Fri Oct 21 14:25:51 JST 2011 i686 GNU/Linux Ubuntu 10.04.3 LTS
- s0711489@ubuntu-lucid:~$ cat > new_hello.c
#include <unistd.h> #include <syscall.h> #include <stdio.h> int main (void) { printf ("new_helloc(1) -> %d\n", syscall(__NR_new_hello, 1) ); }
- s0711489@ubuntu-lucid:~$ gcc -I /lib/modules/2.6.35.14/build/arch/x86/include/ new_hello.c
new_hello.c: In function ‘main’: new_hello.c:8: warning: format ‘%d’ expects type ‘int’, but argument 2 has type ‘long int’
- dmesgにしか出なかったので、KERN_DEBUGを消す
- windell57:i386 s0711489$ make
Kernel: arch/x86/boot/bzImage is ready (#3)
- windell57:i386 s0711489$ make modules
- s0711489@ubuntu-lucid:~$ sudo /mnt/hgfs/tools/install.sh
- s0711489@ubuntu-lucid:~$ sudo reboot
- s0711489@ubuntu-lucid:~$ cat > new_hello.c
- s0711489@ubuntu-lucid:~$ gcc -I /lib/modules/2.6.35.14/build/arch/x86/include/ new_hello.c
- s0711489@ubuntu-lucid:~$ ./a.out
new_helloc(1) -> 1
- s0711489@ubuntu-lucid:~$ dmesg | tail -n 1
[ 116.986628] new_hello() syscall with 1
- KERN_DEBUGを消したが、結局dmesgにしか出ない
- \nの追加
-
arch/x86/kernel/new_hello.c
2 2 #include <linux/syscalls.h> 3 3 4 4 SYSCALL_DEFINE1(new_hello, int, i) { 5 printk( KERN_DEBUG "new_hello() syscall with %d", i);5 printk("new_hello() syscall with %d\n", i); 6 6 return i; 7 7 }
-
- \nの追加
- windell57:i386 s0711489$ make
Kernel: arch/x86/boot/bzImage is ready (#4)
- windell57:i386 s0711489$ make modules
- s0711489@ubuntu-lucid:~$ sudo /mnt/hgfs/tools/install.sh
- s0711489@ubuntu-lucid:~$ cat > new_hello.c
- s0711489@ubuntu-lucid:~$ gcc -I /lib/modules/2.6.35.14/build/arch/x86/include/ new_hello.c
- s0711489@ubuntu-lucid:~$ ./a.out
new_helloc(1) -> 1
- s0711489@ubuntu-lucid:~$ ./a.out 1
new_helloc(2) -> 2
- s0711489@ubuntu-lucid:~$ ./a.out 2
new_helloc(2) -> 2
- s0711489@ubuntu-lucid:~$ ./a.out 3
new_helloc(2) -> 2
- s0711489@ubuntu-lucid:~$ ./a.out 1 2 3 4 5
new_helloc(6) -> 6
- s0711489@ubuntu-lucid:~$ dmesg | tail
[ 62.656820] new_hello() syscall with 1 [ 66.271703] new_hello() syscall with 2 [ 68.411791] new_hello() syscall with 2 [ 70.395934] new_hello() syscall with 2 [ 77.010426] new_hello() syscall with 6
- /var/log/messages /var/log/kern.log /var/log/syslog にも出るようになった
Oct 21 15:29:00 ubuntu-lucid kernel: [ 62.656820] new_hello() syscall with 1 Oct 21 15:29:04 ubuntu-lucid kernel: [ 66.271703] new_hello() syscall with 2 Oct 21 15:29:06 ubuntu-lucid kernel: [ 68.411791] new_hello() syscall with 2 Oct 21 15:29:08 ubuntu-lucid kernel: [ 70.395934] new_hello() syscall with 2 Oct 21 15:29:14 ubuntu-lucid kernel: [ 77.010426] new_hello() syscall with 6
- KERN_DEBUGを戻す
-
arch/x86/kernel/new_hello.c
2 2 #include <linux/syscalls.h> 3 3 4 4 SYSCALL_DEFINE1(new_hello, int, i) { 5 printk( "new_hello() syscall with %d\n", i);5 printk(KERN_DEBUG "new_hello() syscall with %d\n", i); 6 6 return i; 7 7 }
-
- windell57:i386 s0711489$ make
Kernel: arch/x86/boot/bzImage is ready (#5)
- windell57:i386 s0711489$ make modules
- s0711489@ubuntu-lucid:~$ sudo /mnt/hgfs/tools/install.sh
- s0711489@ubuntu-lucid:~$ ./a.out
new_helloc(1) -> 1
- s0711489@ubuntu-lucid:~$ ./a.out 2
new_helloc(2) -> 2
- s0711489@ubuntu-lucid:~$ ./a.out 2 4
new_helloc(3) -> 3
- s0711489@ubuntu-lucid:~$ ./a.out 2 3 4
new_helloc(4) -> 4
- s0711489@ubuntu-lucid:~$ tailf /var/log/syslog
Oct 21 15:39:29 ubuntu-lucid kernel: [ 55.626892] new_hello() syscall with 1 Oct 21 15:40:18 ubuntu-lucid kernel: [ 104.990720] new_hello() syscall with 2 Oct 21 15:40:20 ubuntu-lucid kernel: [ 106.772709] new_hello() syscall with 3 Oct 21 15:40:23 ubuntu-lucid kernel: [ 109.867051] new_hello() syscall with 4
- /var/log/messages には出なくなる
trace sys_new_hello with GDB
- windell57:i386 s0711489$ gdb
(gdb) file vmlinux Reading symbols from /home/ugrad/07/s0711489/coursework/KernelHack/linux-2.6.35.14/i386/vmlinux...(no debugging symbols found)...done. (gdb) b sys_new_hello Breakpoint 1 at 0xc101d87c: file arch/x86/kernel/new_hello.c, line 4. (gdb) target remote localhost:8832 Remote debugging using localhost:8832 0xc1007cdf in native_safe_halt () at /home/ugrad/07/s0711489/coursework/KernelHack/linux-2.6.35.14/i386/arch/x86/include/asm/irqflags.h:49 49 asm volatile("sti; hlt": : :"memory"); (gdb) c Continuing. Breakpoint 1, sys_new_hello (i=1) at arch/x86/kernel/new_hello.c:4 4 SYSCALL_DEFINE1(new_hello, int, i) { (gdb) n 5 printk(KERN_DEBUG "new_hello() syscall with %d\n", i); (gdb) l 1 #include <linux/kernel.h> 2 #include <linux/syscalls.h> 3 4 SYSCALL_DEFINE1(new_hello, int, i) { 5 printk(KERN_DEBUG "new_hello() syscall with %d\n", i); 6 return i; 7 } (gdb) s printk (fmt=0xc1449502 "<7>new_hello() syscall with %d\n") at kernel/printk.c:614 614 va_start(args, fmt); (gdb) l 609 r = vkdb_printf(fmt, args); 610 va_end(args); 611 return r; 612 } 613 #endif 614 va_start(args, fmt); 615 r = vprintk(fmt, args); 616 va_end(args); 617 618 return r; (gdb) n 615 r = vprintk(fmt, args); (gdb) 614 va_start(args, fmt); (gdb) 615 r = vprintk(fmt, args); (gdb) 619 } (gdb) sys_new_hello (i=1) at arch/x86/kernel/new_hello.c:7 7 } (gdb) l 2 #include <linux/syscalls.h> 3 4 SYSCALL_DEFINE1(new_hello, int, i) { 5 printk(KERN_DEBUG "new_hello() syscall with %d\n", i); 6 return i; 7 } (gdb) s
- s0711489@ubuntu-lucid:~$ ./a.out
new_helloc(1) -> 1
add sys_new_hello entry
- windell57:i386 s0711489$ vim include/linux/syscalls.h
-
include/linux/syscalls.h
826 826 unsigned long fd, unsigned long pgoff); 827 827 asmlinkage long sys_old_mmap(struct mmap_arg_struct __user *arg); 828 828 829 asmlinkage long sys_new_hello(int i); 830 829 831 #endif
-
- windell57:i386 s0711489$ make
Kernel: arch/x86/boot/bzImage is ready (#6)
- windell57:i386 s0711489$ make modules
- s0711489@ubuntu-lucid:~$ sudo /mnt/hgfs/tools/install.sh
- s0711489@ubuntu-lucid:~$ ./a.out
new_helloc(1) -> 1
- s0711489@ubuntu-lucid:~$ ./a.out 2
new_helloc(2) -> 2
- s0711489@ubuntu-lucid:~$ ./a.out 2 3
new_helloc(3) -> 3
- s0711489@ubuntu-lucid:~$ tailf /var/log/kern.log
Oct 21 16:16:20 ubuntu-lucid kernel: [ 59.045533] new_hello() syscall with 1 Oct 21 16:16:22 ubuntu-lucid kernel: [ 61.043321] new_hello() syscall with 2 Oct 21 16:16:24 ubuntu-lucid kernel: [ 63.470397] new_hello() syscall with 3
add new system call (x86_64)
- viola04:linux-2.6.35.14 s0711489$ svn cp i386/arch/x86/include/asm/new_hello.h x86_64/arch/x86/include/asm/new_hello.h
- viola04:linux-2.6.35.14 s0711489$ svn cp i386/arch/x86/kernel/new_hello.c x86_64/arch/x86/kernel/
- viola04:linux-2.6.35.14 s0711489$ svn merge i386/include/linux/syscalls.h x86_64/include/linux/syscalls.h -r 1358:1359
10/26
add new system call (x86_64) (cont)
- viola06:x86_64 s0711489$ svn revert include/linux/syscalls.h arch/x86/kernel/new_hello.c arch/x86/include/asm/new_hello.h
- viola06:x86_64 s0711489$ rm arch/x86/kernel/new_hello.c arch/x86/include/asm/new_hello.h
- viola06:linux-2.6.35.14 s0711489$ svn merge i386/arch/ x86_64/arch/ -r1352:1359
- viola06:linux-2.6.35.14 s0711489$ svn merge i386/include/ x86_64/include/ -r1358:1359
- viola04:x86_64 s0711489$ vim arch/x86/include/asm/unistd_64.h
Index: include/linux/syscalls.h =================================================================== --- include/linux/syscalls.h (revision 1367) +++ include/linux/syscalls.h (revision 1368) @@ -826,4 +826,6 @@ unsigned long fd, unsigned long pgoff); asmlinkage long sys_old_mmap(struct mmap_arg_struct __user *arg); +asmlinkage long sys_new_hello(int i); + #endif Index: include =================================================================== --- include (revision 1367) +++ include (revision 1368) Property changes on: include ___________________________________________________________________ Added: svn:mergeinfo Merged /trunk/coursework/KernelHack/linux-2.6.35.14/i386/include:r1359 Index: arch/x86/kernel/syscall_table_32.S =================================================================== --- arch/x86/kernel/syscall_table_32.S (revision 1367) +++ arch/x86/kernel/syscall_table_32.S (revision 1368) @@ -337,3 +337,4 @@ .long sys_rt_tgsigqueueinfo /* 335 */ .long sys_perf_event_open .long sys_recvmmsg + .long sys_new_hello Index: arch/x86/kernel/Makefile =================================================================== --- arch/x86/kernel/Makefile (revision 1367) +++ arch/x86/kernel/Makefile (revision 1368) @@ -131,3 +131,5 @@ obj-$(CONFIG_PCI_MMCONFIG) += mmconf-fam10h_64.o obj-y += vsmp_64.o endif + +obj-y += new_hello.o Index: arch/x86/kernel/new_hello.c =================================================================== --- arch/x86/kernel/new_hello.c (revision 0) +++ arch/x86/kernel/new_hello.c (revision 1368) @@ -0,0 +1,7 @@ +#include <linux/kernel.h> +#include <linux/syscalls.h> + +SYSCALL_DEFINE1(new_hello, int, i) { + printk(KERN_DEBUG "new_hello() syscall with %d\n", i); + return i; +} Index: arch/x86/include/asm/unistd_32.h =================================================================== --- arch/x86/include/asm/unistd_32.h (revision 1367) +++ arch/x86/include/asm/unistd_32.h (revision 1368) @@ -343,10 +343,11 @@ #define __NR_rt_tgsigqueueinfo 335 #define __NR_perf_event_open 336 #define __NR_recvmmsg 337 +#define __NR_new_hello 338 #ifdef __KERNEL__ -#define NR_syscalls 338 +#define NR_syscalls 339 #define __ARCH_WANT_IPC_PARSE_VERSION #define __ARCH_WANT_OLD_READDIR Index: arch/x86/include/asm/new_hello.h =================================================================== --- arch/x86/include/asm/new_hello.h (revision 0) +++ arch/x86/include/asm/new_hello.h (revision 1368) @@ -0,0 +1,7 @@ +#ifndef _ASM_X86_NEW_HELLO_H +#define _ASM_X86_NEW_HELLO_H + +#include <asm/unistd.h> +#define new_hello(x) syscall(__NR_new_hello, x) + +#endif /* _ASM_X86_NEW_HELLO_H */ Index: arch/x86/include/asm/unistd_64.h =================================================================== --- arch/x86/include/asm/unistd_64.h (revision 1367) +++ arch/x86/include/asm/unistd_64.h (revision 1368) @@ -663,6 +663,8 @@ __SYSCALL(__NR_perf_event_open, sys_perf_event_open) #define __NR_recvmmsg 299 __SYSCALL(__NR_recvmmsg, sys_recvmmsg) +#define __NR_new_hello 300 +__SYSCALL(__NR_new_hello, sys_new_hello) #ifndef __NO_STUBS #define __ARCH_WANT_OLD_READDIR Index: arch =================================================================== --- arch (revision 1367) +++ arch (revision 1368) Property changes on: arch ___________________________________________________________________ Added: svn:mergeinfo Merged /trunk/coursework/KernelHack/linux-2.6.35.14/i386/arch:r1353-1359
- viola06:x86_64 s0711489$ make -j 16
Kernel: arch/x86/boot/bzImage is ready (#2)
- viola06:x86_64 s0711489$ make modules
- s0711489@ubuntu-lucid64:~$ sudo /mnt/hgfs/tools/install.sh
- s0711489@ubuntu-lucid64:~/KernelHack/03$ uname -a
Linux ubuntu-lucid64 2.6.32-33-generic #72-Ubuntu SMP Fri Jul 29 21:07:13 UTC 2011 x86_64 GNU/Linux
- s0711489@ubuntu-lucid64:~/KernelHack/03$ gcc -I /lib/modules/2.6.35.14/build/arch/x86/include/ new_hello.c
new_hello.c: In function ‘main’: new_hello.c:9: warning: format ‘%d’ expects type ‘int’, but argument 3 has type ‘long int’
- s0711489@ubuntu-lucid64:~/KernelHack/03$ ./a.out
new_hello(1) -> -1
- reboot 前はsyscallが存在しない
- s0711489@ubuntu-lucid64:~$ sudo reboot
- s0711489@ubuntu-lucid64:~$ uname -a
Linux ubuntu-lucid64 2.6.35.14 #2 SMP Wed Oct 26 13:06:41 JST 2011 x86_64 GNU/Linux
- s0711489@ubuntu-lucid64:~/KernelHack/03$ ./a.out
new_hello(1) -> 1
- s0711489@ubuntu-lucid64:~/KernelHack/03$ ./a.out 2
new_hello(2) -> 2
- s0711489@ubuntu-lucid64:~/KernelHack/03$ ./a.out 2 3
new_hello(3) -> 3
- s0711489@ubuntu-lucid64:~/KernelHack/03$ ./a.out 2 3 4
new_hello(4) -> 4
- s0711489@ubuntu-lucid64:~/KernelHack/03$ tail /var/log/kern.log
Oct 26 13:12:40 ubuntu-lucid64 kernel: [ 40.542158] new_hello() syscall with 1 Oct 26 13:12:42 ubuntu-lucid64 kernel: [ 42.668465] new_hello() syscall with 2 Oct 26 13:12:43 ubuntu-lucid64 kernel: [ 43.908292] new_hello() syscall with 3 Oct 26 13:12:45 ubuntu-lucid64 kernel: [ 45.645548] new_hello() syscall with 4
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- gdb.getpid.log (2.1 KB) - added by mitty 13 years ago.
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